In a paper conveyance apparatus provided in an apparatus such as an image reading apparatus and an image copying apparatus, a jam occurs in some cases when a paper moves in a conveyance path. Some paper conveyance apparatuses include a function for determining whether a jam has occurred based on whether a paper has been conveyed to a predetermined position in a conveying path within a predetermined period of time after initiation of conveyance of the paper to stop an operation of the apparatus when a jam has occurred.
As a technique relating to jam detection, a jam detection apparatus of a copier including an acoustic electric signal conversion unit disposed in the vicinity of a sheet conveyance path, a level detector that compares an output of the acoustic electric signal conversion unit with a baseline level to generate a pulse signal while the output exceeds the baseline level, and a pulse width detector that compares a duration of a pulse signal from the level detector with a reference value is known.
Related art is disclosed in Japanese Laid-open Patent Publication No. 57-169767.